Molecular homogeneity in diverse geographical populations of Phlebotomus papatasi (Diptera, Psychodidae) inferred from ND4 mtDNA and ITS2 rDNA

Population structure analysis of Phlebotomus papatasi populations using transcriptome microsatellites: possible implications for leishmaniasis control and vaccine development

BACKGROUND

Phlebotomus papatasi is considered the primary vector of Leishmania major parasites that cause zoonotic cutaneous leishmaniasis (ZCL) in the Middle East and North Africa. Phlebotomus papatasi populations have been studied extensively, revealing the existence of different genetic populations and subpopulations over its large distribution range. Genetic diversity and population structure analysis using transcriptome microsatellite markers is important to uncover the vector distribution dynamics, essential for controlling ZCL in endemic areas.

METHODS

In this study, we investigated the level of genetic variation using expressed sequence tag-derived simple sequence repeats (EST-SSRs) among field and colony P. papatasi samples collected from 25 different locations in 11 countries. A total of 302 P. papatasi sand fly individuals were analyzed, including at least 10 flies from each region.

RESULTS

The analysis revealed a high-level population structure expressed by five distinct populations A through E, with moderate genetic differentiation among all populations. These genetic differences in expressed genes may enable P. papatasi to adapt to different environmental conditions along its distribution range and likely affect dispersal.

CONCLUSIONS

Elucidating the population structuring of P. papatasi is essential to L. major containment efforts in endemic countries. Moreover, the level of genetic variation among these populations may improve our understanding of Leishmania-sand fly interactions and contribute to the efforts of vaccine development based on P. papatasi salivary proteins.

Genetic diversity and phylogeography of Phlebotomus argentipes (Diptera: Psychodidae, Phlebotominae), using COI and ND4 mitochondrial gene sequences

BACKGROUND

Phlebotomus argentipes complex is the primary vector for cutaneous leishmaniasis, a burgeoning health concern in contemporary Sri Lanka, where effective vector control is important for proper disease management. Understanding the genetic diversity of the P. argentipes population in Sri Lanka is vital before implementing a successful vector control program. Various studies have indicated that genetic divergence, caused by genetic drift or selection, can significantly influence the vector capacity of arthropod species. To devise innovative control strategies for P. argentipes, exploring genetic diversity and phylogeography can offer valuable insights into vector competence, key genetic trait transfer, and impact on disease epidemiology. The primary objective is to analyze the genetic diversity and phylogeography of the P. argentipes complex in Sri Lanka, based on two mitochondrial genomic regions in modern representatives of P. argentipes populations.

METHODOLOGY

A total of 159 P. argentipes specimens were collected from five endemic areas of cutaneous leishmaniasis and identified morphologically. Two mitochondrial regions (Cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit 4 (ND4) were amplified using the total DNA and subsequently sequenced. Partial sequences of those mitochondrial genes were utilized to analyze genetic diversity indices and to explore phylogenetic and phylogeographic relationships.

PRINCIPAL FINDINGS

Among five sampling locations, the highest genetic diversity for COI and ND4 was observed in Hambantota (Hd-0.749, π-0.00417) and Medirigiriya (Hd-0.977, π-0.01055), respectively. Phylogeographic analyses conducted using COI sequences and GenBank retrieved sequences demonstrated a significant divergence of P. argentipes haplotypes found in Sri Lanka. Results revealed that they have evolved from the Indian ancestral haplotype due to historical- geographical connections of the Indian subcontinent with Sri Lanka.

CONCLUSIONS

Utilizing high-mutation-rate mitochondrial genes, such as ND4, can enhance the accuracy of genetic variability analysis in P. argentipes populations in Sri Lanka. The phylogeographical analysis of COI gene markers in this study provides insights into the historical geographical relationship between India and P. argentipes in Sri Lanka. Both COI and ND4 genes exhibited consistent genetic homogeneity in P. argentipes in Sri Lanka, suggesting minimal impact on gene flow. This homogeneity also implies the potential for horizontal gene transfer across populations, facilitating the transmission of genes associated with traits like insecticide resistance. This dynamic undermines disease control efforts reliant on vector control strategies.

Reconstructing the post-glacial spread of the sand fly Phlebotomus mascittii Grassi, 1908 (Diptera: Psychodidae) in Europe

Phlebotomine sand flies (Diptera: Phlebotominae) are the principal vectors of Leishmania spp. (Kinetoplastida: Trypanosomatidae). In Central Europe, Phlebotomus mascittii is the predominant species, but largely understudied. To better understand factors driving its current distribution, we infer patterns of genetic diversity by testing for signals of population expansion based on two mitochondrial genes and model current and past climate and habitat suitability for seven post-glacial maximum periods, taking 19 climatic variables into account. Consequently, we elucidate their connections by environmental-geographical network analysis. Most analyzed populations share a main haplotype tracing back to a single glacial maximum refuge area on the Mediterranean coasts of South France, which is supported by network analysis. The rapid range expansion of Ph. mascittii likely started in the early mid-Holocene epoch until today and its spread possibly followed two routes. The first one was through northern France to Germany and then Belgium, and the second across the Ligurian coast through present-day Slovenia to Austria, toward the northern Balkans. Here we present a combined approach to reveal glacial refugia and post-glacial spread of Ph. mascittii and observed discrepancies between the modelled and the current known distribution might reveal yet overlooked populations and potential further spread.

Molecular identification of phlebotomine sand flies and the harbored Leishmania spp. in Sokoto State, Nigeria

Introduction

Female sand flies are hematophagous, feeding on animals and in the process serve as vectors for Leishmania, the parasites that cause leishmaniasis in humans. Leishmaniasis are a group of parasitic neglected tropical diseases in 98 countries including Nigeria and kills ~60,000 people/year. In Nigeria, Sokoto State is endemic to leishmaniasis but there is a knowledge gap on the identity of the prevalent sand flies and the Leishmania species they transmit. Hence, this cross-sectional study was designed to take inventory of the species of sand flies in Sokoto using genetic methods.

Methods

1,260 (310 females) sand flies were collected from three Local Government Areas (L.G.A) of Sokoto State- Wamakko, Sokoto South and Kware. Genomic DNA was extracted from each fly and DNA amplification by polymerase chain reaction (PCR) was carried out on the DNA samples using primers targeting the arthropods mitochondrial cytochrome oxidase subunit 1 (mt-coI) gene, and nested PCR with primers targeting the gene for Leishmania internal transcribed spacer-1 (its-1) of ribosomal RNA its-1rRNA. The PCR products were sequenced.

Results

Gene sequence analysis revealed five species of sand flies belonging to the old-world genera namely Phlebotomus and Sergentomyia. The identified species were P. papatasi (6.45%), S. adleri (6.45%), S. affinis (9.7%), S. distincta (9.7%), S. schwetzi (67.7%). Within the sampling period, sand flies were most abundant in the rainy months of August (104/33.5%) and September (116/37.4%) with all the five identified species occurring. Sequence analysis of its-1 gene identified Leishmania infantum in two sand flies (2/310)- P. papatasi (from Sokoto South) and S. affinis (from Wamakko). BLAST search in NCBI and phylogenetic analysis revealed that the sand fly species are related to the species reported in different parts of Africa, while the L. infantum is identical to strain reported in Brazil (KY379083.1).

Discussion

Phlebotomus papatasi and four species belonging to the genus Sergentomyia are the most prevalent sand flies in Sokoto State, Nigeria and they harbor L. infantum solely. The results shed light on why visceral leishmaniasis is the most predominant form of the disease. Therefore, we recommend that adequate care for dogs must be instituted as dogs are the major animal reservoir for L. infantum.

Genetic diversity, phylogenetic and phylogeographic analysis of Anopheles culicifacies species complex using ITS2 and COI sequences

Anopheles culicifacies is the major vector of malaria in Sri Lanka and the Indian subcontinent which is characterized as a species complex with five sibling species provisionally designated as A, B, C, D and E. The current study was carried out to understand the phylogenetic and phylogeographic relationships between the sibling species of the species complex while observing their genetic diversity and genetic differentiation. Thirty-five ITS2 and seventy-seven COI sequences of An. culicifacies species complex reported from different geographical locations of Asia and China at the NCBI public database were used for the analysis. Bayesian likelihood trees were generated for the phylogenetic analysis. The divergence of the species complex was obtained from the Bayesian phylogeographic model in BEAST. There were two clades of the sibling species of An. culicifacies species complex as A, D and B, C and E in both phylogenetic and phylogeographic analysis using ITS2 sequences. Based on the highly divergent COI sequences and the high mutation rate of the mitochondrial genome, there were four and three clades in both phylogenetic and phylogeographic analysis using COI sequences. The diversification of An. culicifacies species complex was obtained as ranging from 20.25 to 24.12 Mya and 22.37 to 26.22 Mya based on ITS2 and COI phylogeographic analysis respectively. There was a recent diversification of the sibling species A and D than the sibling species B, C and E. Low haplotype diversity was observed in the sequences reported from Sri Lanka in both ITS2 and COI analysis that can be due to bottlenecks resulting from the intense malaria control efforts. A high genetic differentiation was achieved for some populations due to the large geographical distance. The high genetic diversity based on the five sibling species implies the possibility of maintaining a relatively high effective population size despite the vector control efforts.

Genomic analysis of two phlebotomine sand fly vectors of Leishmania from the New and Old World

Phlebotomine sand flies are of global significance as important vectors of human disease, transmitting bacterial, viral, and protozoan pathogens, including the kinetoplastid parasites of the genus Leishmania, the causative agents of devastating diseases collectively termed leishmaniasis. More than 40 pathogenic Leishmania species are transmitted to humans by approximately 35 sand fly species in 98 countries with hundreds of millions of people at risk around the world. No approved efficacious vaccine exists for leishmaniasis and available therapeutic drugs are either toxic and/or expensive, or the parasites are becoming resistant to the more recently developed drugs. Therefore, sand fly and/or reservoir control are currently the most effective strategies to break transmission. To better understand the biology of sand flies, including the mechanisms involved in their vectorial capacity, insecticide resistance, and population structures we sequenced the genomes of two geographically widespread and important sand fly vector species: Phlebotomus papatasi, a vector of Leishmania parasites that cause cutaneous leishmaniasis, (distributed in Europe, the Middle East and North Africa) and Lutzomyia longipalpis, a vector of Leishmania parasites that cause visceral leishmaniasis (distributed across Central and South America). We categorized and curated genes involved in processes important to their roles as disease vectors, including chemosensation, blood feeding, circadian rhythm, immunity, and detoxification, as well as mobile genetic elements. We also defined gene orthology and observed micro-synteny among the genomes. Finally, we present the genetic diversity and population structure of these species in their respective geographical areas. These genomes will be a foundation on which to base future efforts to prevent vector-borne transmission of Leishmania parasites.

Genetic variability highlights the invasion route of the Lutzomyia longipalpis complex, the main vector of Visceral Leishmaniasis in Uruguay

In the Americas, the sandfly Lutzomyia longipalpis is the main vector of the parasitic protozoa Leishmania infantum, the etiological agent of visceral leishmaniasis (VL). The Lu. longipalpis species complex is currently discontinuously distributed across the Neotropical region, from Mexico to the north of Argentina and Uruguay. During its continental spreading, it must have adapted to several biomes and temperature amplitudes, when founder events should have contributed to the high genetic divergence and geographical structure currently observed, reinforcing the speciation process. The first report of Lu. longipalpis in Uruguay was in 2010, calling the attention of Public Health authorities. Five years later, the parasite Le. infantum was recorded and in 2015 the first case of VL in canids was reported. Hitherto seven human cases by VL have been reported in Uruguay. Here, we publish the first DNA sequences from the mitochondrial genes ND4 and CYTB of Lu. longipalpis collected in Uruguay, and we used these molecular markers to investigate their genetic variability and population structure. We described four new ND4 haplotypes in a total of 98 (4/98) and one CYTB in a total of 77 (1/77). As expected, we were able to establish that the Lu. longipalpis collected in two localities (i.e. Salto and Bella Unión) from the north of Uruguay are closely related to the populations from neighbouring countries. We also propose that the possible route for the vector arrival to the region may have been through vegetation and forest corridors of the Uruguay River system, as well as it may have benefited from landscape modifications generated by commercial forestation. The ecological-scale processes shaping Lu. longipalpis populations, the identification of genetically homogeneous groups and the gene flow among them must be carefully investigated by using highly sensible molecular markers (i.e. genome wide SNPs) since it will help to the understanding of VL transmission and contribute to the planification of public policies on its control.

Ecological Survey of the Peridomestic Sand Flies of an Endemic Focus of Zoonotic Cutaneous Leishmaniasis in the South-East of Morocco

Leishmaniasis is a parasitosis caused by parasites of the genus Leishmania and is transmitted by Phlebotominae sand flies. An entomological survey was carried out in different localities of Zagora Province. Our work allowed us to establish an inventory of sand flies to study potential vectors of leishmaniasis and to compare the composition and the specific abundance of different endemic stations. The sand flies were collected using CDC miniature light traps during the month of July 2019 in the ten studied villages. The results indicate the presence of thirteen species, belonging to the genera Phlebotomus and Sergentomyia. Phlebotomus papatasi was the predominant species (46.65%) followed by Ph. alexandri (17%), Ph. longicuspis (11.55%), Ph. bergeroti (1.53%) and Ph. sergenti (1.27%). Phlebotomus kazeruni (0.03%) was rare, and only one female was captured in Ifred. Sergentomyia schwetzi (8.69%) was the most prevalent species in the Sergentomyia genus followed closely by Se. fallax (6.84%). Sergentomyia africana was present with a proportion of (3.86%) followed by Se. clydei (1.96%). Sergentomyia dreifussi (0.46%), Se. antennata (0.08%), and Se. minuta (0.08%) were very limited. Phlebotomus papatasi, Ph. alexandri, Ph. bergeroti, Ph. longicuspis, Ph. sergenti, Se. schwetzi, Se. clydei, and Se. fallax are constant species, being present at least in 50% of the stations (occurrence> 50%). Common species (25%–49%) were Se. minuta and Se. africana and rare species were Ph. kazeruni and Se. antennata with a very limited distribution (occurrence <12%). The greatest species richness was found in Ksar Mougni and Ifred with the occurrence of 11 species, but overall, it was high (>9 species) in most of the villages. The Shannon–Wiener index was high (H′ > 1) in eight localities (Ksar Mougni, Tassaouante, Bleida, ZaouiteLeftah, Ifred, Timarighine, Ait Oulahyane, and Ait Ali Ouhassou). The high value of this index is in favor of the ZaouiteLeftah locality (Shannon–Wiener index = 1.679) which is explained by the presence of a stand dominated by Ph. papatasi. In order to avoid exposure to infections, a good epidemiological surveillance and vector with rodent control measures must be well maintained. Awareness campaigns are also required and must be conducted for better knowledge of the disease.

Phlebotomine sand fly survey in the Republic of Moldova: species composition, distribution and host preferences

BACKGROUND

Phlebotomine sand flies (Diptera: Psychodiae) in the Republic of Moldova have been understudied for decades. Our study provides a first update on their occurrence, species composition and bloodmeal sources after 50 years.

METHODS

During 5 seasons (2013-2017), 58 localities from 20 regions were surveyed for presence of sand flies using CDC light traps and manual aspirators. Species identification was done by a combination of morphological and molecular approaches (DNA barcoding, MALDI-TOF MS protein profiling). In engorged females, host blood was identified by three molecular techniques (RFLP, cytb sequencing and MALDI-TOF peptide mass mapping). Population structure of most abundant species was studied by cox1 haplotyping; phylogenetic analyses of ITS2 and cox1 genetic markers were used to resolve relationships of other detected species.

RESULTS

In total, 793 sand flies were collected at 30 (51.7%) localities from 12 regions of Moldova. Three species were identified by an integrative morphological and molecular approach: Phlebotomus papatasi, P. perfiliewi and Phlebotomus sp. (Adlerius), the first being the most abundant and widespread, markedly anthropophilic based on bloodmeal analyses, occurring also indoors and showing low population structure with only five haplotypes of cox1 detected. Distinct morphological and molecular characters of Phlebotomus sp. (Adlerius) specimens suggest the presence of a yet undescribed species.

CONCLUSIONS

Our study revealed the presence of stable sand fly populations of three species in Moldova that represent a biting nuisance as well as a potential threat of pathogen transmission and shall be further studied.

First molecular identification of Leishmania major in Phlebotomus papatasi in an outbreak cutaneous leishmaniasis area in Iraq

Cutaneous leishmaniasis (CL) is transmitted by Phlebotomine sand fly vectors, among which Phlebotomus papatasi is prevalent in Western Asia, Northern Africa and Southern Europe, and it is known as a vector for Leishmania major parasite in the world. However, in Iraq, morphological studies showed that P. papatasi is a predominant sand fly species and hypothesised to transmit CL causing Leishmania species including L. major and L. tropica. Few studies have found Leishmania species in sand flies in mixed pools of samples in this country. Accurate identification of sand flies as vectors of Leishmania species is required in Iraq. The current study aims to identify sand fly species, using both morphological and molecular phylogenetic analyses, in a region where CL tends to be endemic. Furthermore, molecular phylogenetic analysis has also used to confirm Leishmania species in the sand fly samples collected in 11 villages between Diyala and Sulaymaniyah Provinces. For the first time, we have found L. major in three individual sand flies, one engorged (with fresh blood meal) and two non-engorged (without visible fresh blood meal) P. papatasi females in an area of CL outbreaks since 2014-till now due to civil wars and internal conflicts happen in the region. Further study should be performed on sand fly population and Leishmania reservoirs in this region.

Hybridization in Phlebotominae (Diptera: Psychodidae): A mini-review

Taxonomy based only on morphology, although extremely important for the classification of sandflies, has been shown to be insufficient for the delimitation of some taxa. Thus, integrative taxonomy could play a fundamental role in clarifying these and other taxonomic issues, since data from different areas are used to aggregate greater reliability in species classification. Experimental crosses are important taxonomic tools, since the presence of reproductive barriers when associated with divergence between two evolutionary lineages, confirms the specific status of taxa based on the biological species concept. In the subfamily Phlebotominae, experimental crosses were mostly focused on the study of the Lutzomyia longipalpis complex, which helped to identify different evolutionary lineages for that group of vectors. Considering the difficulty of classifying some Phlebotominae species and the importance of hybridization studies for taxonomy, we grouped all the information associated with experimental crosses in sandflies in a mini-review. In view of the results grouped in this review, it is evident that i) experimental crossings are important tools to aggregate studies of integrative taxonomy in the Phlebotominae subfamily; ii) these analyses should be applied in the taxonomic studies of cryptic species; iii) Lu longipalpis populations have pre and/or post-zygotic reproductive barriers; iv) Lu. longipalpis represents more than one species and efforts must be applied to differentiate the taxa of the Lu. longipalpis complex; v) Phlebotomus populations do not present intraspecific reproductive barriers; vi) the absence of reproductive barriers between Ph. sergenti from Israel and Turkey (representing populations of the same evolutionary lineage) does not rule out the possible existence of cryptic species, it being necessary to perform experimental crosses between the different strains indicated by the molecular markers; and finally, vii) different species of Phlebotomus have post-zygotic barriers, confirming the specific status of Ph. duboscqi, Ph. papatasi, and Ph. bergeroti.

Phlebotomus papatasi sand fly predicted salivary protein diversity and immune response potential based on in silico prediction in Egypt and Jordan populations

Phlebotomus papatasi sand flies inject their hosts with a myriad of pharmacologically active salivary proteins to assist with blood feeding and to modulate host defenses. In addition, salivary proteins can influence cutaneous leishmaniasis disease outcome, highlighting the potential of the salivary components to be used as a vaccine. Variability of vaccine targets in natural populations influences antigen choice for vaccine development. Therefore, the objective of this study was to investigate the variability in the predicted protein sequences of nine of the most abundantly expressed salivary proteins from field populations, testing the hypothesis that salivary proteins appropriate to target for vaccination strategies will be possible. PpSP12, PpSP14, PpSP28, PpSP29, PpSP30, PpSP32, PpSP36, PpSP42, and PpSP44 mature cDNAs from field collected P. papatasi from three distinct ecotopes in the Middle East and North Africa were amplified, sequenced, and in silico translated to assess the predicted amino acid variability. Two of the predicted sequences, PpSP12 and PpSP14, demonstrated low genetic variability across the three geographic isolated sand fly populations, with conserved multiple predicted MHCII epitope binding sites suggestive of their potential application in vaccination approaches. The other seven predicted salivary proteins revealed greater allelic variation across the same sand fly populations, possibly precluding their use as vaccine targets.

Population Genetics of Phlebotomus papatasi from Endemic and Nonendemic Areas for Zoonotic Cutaneous Leishmaniasis in Morocco, as Revealed by Cytochrome Oxidase Gene Subunit I Sequencing

Zoonotic cutaneous leishmaniasis (ZCL) caused by Leishmania major Yakimoff & Shokhor and transmitted by Phlebotomus papatasi (Scopoli) is a public health concern in Morocco. The disease is endemic mainly in pre-Saharan regions on the southern slope of the High Atlas Mountains. The northern slope of the High Atlas Mountains and the arid plains of central Morocco remain non-endemic and are currently considered high risk for ZCL. Here we investigate and compare the population genetic structure of P. papatasi populations sampled in various habitats in historical foci and non-endemic ZCL areas. A fragment of the mtDNA cytochrome oxidase I (COI) gene was amplified and sequenced in 59 individuals from 10 P. papatasi populations. Haplotype diversity was probed, a median-joining network was generated (F_ST) and molecular variance (AMOVA) were analyzed. Overall, we identified 28 haplotypes with 32 distinct segregating sites, of which seven are parsimony informative. The rate of private haplotypes was high; 20 haplotypes (71.4%) are private ones and exclusive to a single population. The phylogenetic tree and the network reconstructed highlight a genetic structuration of these populations in two well defined groups: Ouarzazate (or endemic areas) and Non-Ouarzazate (or nonendemic areas). These groups are separated by the High Atlas Mountains. Overall, our study highlights differences in terms of population genetics between ZCL endemic and non-endemic areas. To what extent such differences would impact the transmission of L. major by natural P. papatasi population remains to be investigated.

Genetic Structure of Phlebotomus orientalis (Diptera: Psychodidae) in Leishmaniasis Endemic Foci of Sudan

BACKGROUND AND OBJECTIVE

Visceral leishmaniasis (VL) remains a major concern in many parts of Sudan. The disease is transmitted by Phlebotomus orientalis. The objective of this study was to determine genetic structure of Phlebotomus orientalis population from 5 geographical regions in Sudan.

MATERIALS AND METHODS

A total of 194 individual sand flies were collected from 5 geographic regions in Sudan. The field collected sand flies were analyzed by Random Amplified Polymorphic DNA (RAPD) using 30 primers.

RESULTS

Eight hundred and 65 bands from 4 RAPD primers were analyzed for genetic variation. A higher level of intrapopulational variability was detected in populations of P. orientalis from eastern Sudan compared to those populations from central and northern Sudan. Diagnostic bands were detected in populations of P. orientalis central Sudan. Hieratical clustering analysis showed clear clustering into 2 main populations with 1 population subdivided into 4 subpopulations. However, these populations did not show any correlation with their geographical origins. Furthermore, the low genetic differentiation among subpopulations was supported by fixation index (FST) estimated by analysis of molecular variance (AMOVA).

CONCLUSION

It is concluded that the populations of P. orientalis from the selected areas in Sudan have a low genetic differentiation. However, assessment of genetic structure of P. orientalis populations is important for understanding the patterns of transmission of VL in different endemic areas.

Revision of the species composition and distribution of Turkish sand flies using DNA barcodes

Background

Currently, knowledge regarding the phlebotomine sand fly (Diptera: Psychodidae) fauna of Turkey is restricted to regions with endemic leishmaniasis. However, rapidly changing environmental and social conditions highlight concerns on the possible future expansion of sand fly-borne diseases in Turkey, promoting risk assessment through biosurveillance activities in non-endemic regions. Traditional morphological approaches are complicated by extensive cryptic speciation in sand flies, thus integrated studies utilizing DNA markers are becoming increasingly important for correct sand fly identification. This study contributes to the knowledge of the sand fly fauna in understudied regions of Turkey, and provides an extensive DNA barcode reference library of expertly identified Turkish sand fly species for the first time.

Methods

Fly sampling was conducted at 101 locations from 29 provinces, covering all three biogeographical regions of Turkey. Specimens were morphologically identified using available keys. Cytochrome c oxidase I (cox1) barcode sequences were analyzed both for morphologically distinct species and those specimens with cryptic identity. A taxon identity tree was obtained using Neighbor Joining (NJ) analysis. Species boundaries among closely related taxa evaluated using ABGD, Maximum Likelihood (ML) and haplotype network analyses. Sand fly richness of all three biogeographical regions were compared using nonparametric species richness estimators.

Results

A total of 729 barcode sequences (including representatives of all previously reported subgenera) were obtained from a total of 9642 sand fly specimens collected in Turkey. Specimens belonging to the same species or species complex clustered together in the NJ tree, regardless of their geographical origin. The species delimitation methods revealed the existence of 33 MOTUs, increasing the previously reported 28 recorded sand fly species by 17.8%. The richest sand fly diversity was determined in Anatolia, followed by the Mediterranean, and then the Black Sea regions of the country.

Conclusions

A comprehensive cox1 reference library is provided for the sand fly species of Turkey, including the proposed novel taxa discovered herein. Our results have epidemiological significance exposing extensive distributions of proven and suspected sand fly vectors in Turkey, including those areas currently regarded as non-endemic for sand fly-borne disease.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3669-3) contains supplementary material, which is available to authorized users.

Ecological niche modeling predicting the potential distribution of Leishmania vectors in the Mediterranean basin: impact of climate change

Background

Due to climate change, the geographical distribution of sand flies during the last decades has shifted northward from latitudes below 45°N in southern Europe to latitudes just above 50^○N. Recent studies show that some phlebotomine sand flies were recorded in several parts of Germany and Belgium. In central Europe, some autochthone leishmaniasis cases are being recorded in regions traditionally regarded as leishmaniasis-free. An important challenge is to predict the geographical distribution of leishmaniasis vectors under new climatic conditions. In this study, we attempted to predict the current distribution of six leishmaniasis vectors in the Mediterranean basin and forecast species’ geographical shift under future climate scenarios using an ensemble ecological niche modeling approach. Species records were obtained from scientific surveys published in the research literature between 2006 and 2016. A series of climate metrics describing temperature and precipitation in the study area under two climatic scenarios were obtained from WorldClim database. A consensus model was derived from six varieties of modeling approaches (regression, machine learning and classification techniques) in order to ensure valid prediction of distribution of vectors under different climate scenarios.

Results

Model performance was generally high for the included species with a specificity (true negative rate) ranging from 81.03 to 96.52% (mean = 86.94%) and a sensitivity (true positive rate) ranging from 87.93 to 100% (mean = 96.98%). Our work evidenced the hypothesis of the widespread of Leishmania vectors under climate change scenarios. All of the studied species are prospected to gain new areas that are actually not suitable for vectors’ survival. Phlebotomine sand flies are prospected to invade extra-Mediterranean regions, especially western and central Europe.

Conclusions

Our study confirmed the importance of environmental and climate factors on the distribution of leishmaniasis vectors and demonstrated the performance of ecological niche modeling in the prediction of the geographical spread of vector-borne diseases. Ecological niche modeling should be considered in the future as a valuable tool in addition to experimental laboratory studies for a better understanding of the biology of vector species.

Genetic diversity, phylogeography and molecular clock of the Lutzomyia longipalpis complex (Diptera: Psychodidae)

BACKGROUND

The Lutzomyia longipalpis complex has a wide but discontinuous distribution in Latin America, extending throughout the Neotropical realm between Mexico and northern Argentina and Uruguay. In the Americas, this sandfly is the main vector of Leishmania infantum, the parasite responsible for Visceral Leishmaniasis (VL). The Lu. longipalpis complex consists of at least four sibling species, however, there is no current consensus on the number of haplogroups, or on their divergence. Particularly in Argentina, there have been few genetic analyses of Lu. longipalpis, despite its southern expansion and recent colonization of urban environments. The aim of this study was to analyze the genetic diversity and structure of Lu. longipalpis from Argentina, and to integrate these data to re-evaluate the phylogeography of the Lu. longipalpis complex using mitochondrial markers at a Latin American scale.

METHODOLOGY/PRINCIPAL FINDINGS

Genetic diversity was estimated from six sites in Argentina, using a fragment of the ND4 and the 3´ extreme of the cyt b genes. Greatest genetic diversity was found in Tartagal, Santo Tomé and San Ignacio. There was high genetic differentiation of Lu. longipalpis in Argentina using both markers: ND4 (FST = 0.452, p < 0.0001), cyt b (FST = 0.201, p < 0.0001). Genetic and spatial Geneland analyses reveal the existence of two primary genetic clusters in Argentina, cluster 1: Tartagal, Santo Tomé, and San Ignacio; cluster 2: Puerto Iguazú, Clorinda, and Corrientes city. Phylogeographic analyses using ND4 and cyt b gene sequences available in GenBank from diverse geographic sites suggest greater divergence than previously reported. At least eight haplogroups (three of these identified in Argentina), each separated by multiple mutational steps using the ND4, are differentiated across the Neotropical realm. The divergence of the Lu. longipalpis complex from its most recent common ancestor (MRCA) was estimated to have occurred 0.70 MYA (95% HPD interval = 0.48-0.99 MYA).

CONCLUSIONS/SIGNIFICANCE

This study provides new evidence supporting two Lu. longipalpis genetic clusters and three of the total eight haplogroups circulating in Argentina. There was a high level of phylogeographic divergence among the eight haplogroups of the Lu. longipalpis complex across the Neotropical realm. These findings suggest the need to analyze vector competence, among other parameters intrinsic to a zoonosis, according to vector haplogroup, and to consider these in the design and surveillance of vector and transmission control strategies.

Population genetics analysis of Phlebotomus papatasi sand flies from Egypt and Jordan based on mitochondrial cytochrome b haplotypes

BACKGROUND

Phlebotomus papatasi sand flies are major vectors of Leishmania major and phlebovirus infection in North Africa and across the Middle East to the Indian subcontinent. Population genetics is a valuable tool in understanding the level of genetic variability present in vector populations, vector competence, and the development of novel control strategies. This study investigated the genetic differentiation between P. papatasi populations in Egypt and Jordan that inhabit distinct ecotopes and compared this structure to P. papatasi populations from a broader geographical range.

METHODS

A 461 base pair (bp) fragment from the mtDNA cytochrome b (cyt b) gene was PCR amplified and sequenced from 116 individual female sand flies from Aswan and North Sinai, Egypt, as well as Swaimeh and Malka, Jordan. Haplotypes were identified and used to generate a median-joining network, F _ST values and isolation-by-distance were also evaluated. Additional sand fly individuals from Afghanistan, Iran, Israel, Jordan, Libya, Tunisia and Turkey were included as well as previously published haplotypes to provide a geographically broad genetic variation analysis.

RESULTS

Thirteen haplotypes displaying nine variant sites were identified from P. papatasi collected in Egypt and Jordan. No private haplotypes were identified from samples in North Sinai, Egypt, two were observed in Aswan, Egypt, four from Swaimeh, Jordan and two in Malka, Jordan. The Jordan populations clustered separately from the Egypt populations and produced more private haplotypes than those from Egypt. Pairwise F _ST values fall in the range 0.024-0.648.

CONCLUSION

The clustering patterns and pairwise F _ST values indicate a strong differentiation between Egyptian and Jordanian populations, although this population structure is not due to isolation-by-distance. Other factors, such as environmental influences and the genetic variability in the circulating Le. major parasites, could possibly contribute to this heterogeneity. The present study aligns with previous reports in that pockets of genetic differentiation exists between populations of this widely dispersed species but, overall, the species remains relatively homogeneous.

Development of polymorphic EST microsatellite markers for the sand fly, Phlebotomus papatasi (Diptera: Psychodidae)

Background

Phlebotomus papatasi is a widely distributed sand fly species in different tropical and sub-tropical regions including the Middle East and North Africa. It is considered an important vector that transmits Leishmania major parasites, the causative agents of cutaneous leishmaniasis. The development of microsatellite markers for this sand fly vector is of high interest to understand its population structure and to monitor its geographic dispersal.

Results

Fourteen polymorphic microsatellite markers were developed with simple di-, tri- and tetra-nucleotide repeats. The F statistics calculated for the 14 markers revealed high genetic diversity; expected heterozygosity (He) ranged from 0.407 to 0.767, while observed heterozygosity (Ho) was lower and ranged from 0.083 to 0.514. The number of alleles sampled fall in the range of 9–29. Three out of 14 markers deviated from Hardy-Weinberg expectations, no significant linkage disequilibrium was detected and high values for inbreeding coefficient (F_IS) were likely due to inbreeding.

Conclusions

The development of these functional microsatellites enable a high resolution of P. papatasi populations. It opens a path for researchers to perform multi locus-based population genetic structure analyses, and comparative mapping, a part of the efforts to uncover the population dynamics of this vector, which is an important global strategy for understanding the epidemiology and control of leishmaniasis.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2770-3) contains supplementary material, which is available to authorized users.

Identification of wild-caught phlebotomine sand flies from Crete and Cyprus using DNA barcoding

Background

Phlebotomine sand flies (Diptera: Psychodidae) are vectors of Leishmania spp., protozoan parasites responsible for a group of neglected diseases called leishmaniases. Two sand fly genera, Phlebotomus and Sergentomyia, contain species that are present in the Mediterranean islands of Crete and Cyprus where the visceral (VL), cutaneous (CL) and canine (CanLei) leishmaniases are a public health concern. The risk of transmission of different Leishmania species can be studied in an area by monitoring their vectors. Sand fly species are traditionally identified using morphological characteristics but minute differences between individuals or populations could be overlooked leading to wrong epidemiological predictions. Molecular identification of these important vectors has become, therefore, an essential tool for research tasks concerning their geographical distribution which directly relates to leishmaniasis control efforts. DNA barcoding is a widely used molecular identification method for cataloguing animal species by sequencing a fragment of the mitochondrial gene encoding cytochrome oxidase I.

Results

DNA barcoding was used to identify individuals of five sand fly species (Phlebotomus papatasi, P. similis, P. killicki, Sergentomyia minuta, S. dentata) circulating in the islands of Crete and Cyprus during the years 2011–2014. Phlebotomus papatasi is a known vector of zoonotic CL in the Middle East and it is found in both islands. Phlebotomus similis is the suspected vector of Leishmania tropica in Greece causing anthroponotic CL. Phlebotomus killicki was collected in Cyprus for the first time. Sergentomyia minuta, found to present intraspecific diversity, is discussed for its potential as a Leishmania vector. Molecular identification was consistent with the morphological identification. It successfully identified males and females, which is difficult when using only morphological characters. A phylogenetic tree was constructed based on the barcodes acquired, representing their genetic relationships along with other species from the area studied. All individuals identified were clustered according to their species and subgenus.

Conclusions

Molecular identification of sand flies via DNA barcoding can accurately identify these medically important insects assisting traditional morphological tools, thus helping to assess their implication in Leishmania transmission.

Molecular Identification of Phlebotomus caucasicus and Phlebotomus mongolensis (Diptera: Psychodidae) in a Hyperendemic Area of Zoonotic Cutaneous Leishmaniasis in Iran

Phlebotomus caucasicus Marzinovsky and Phlebotomus mongolensis Sinton are morphologically similar sand fly species. Finding a reliable, fast, and simple method to differentiate these two sand flies is important in understanding their role in the transmission of Leishmania parasite. In our study, 20 specimens of male P. caucasicus, 4 specimens of male P. mongolensis, and 16 specimens of female of both species (Caucasicus group) were examined by polymerase chain reaction (PCR). The result shows identical patterns with a visible fragment of about 500 bp in size. In restriction fragment length polymorphism (RFLP), we observed identical patterns with TasI used as the restriction enzyme. After alignment with sequences of the ITS2 partial gene in GenBank, a perfect match was obtained for the P. mongolensis, but not for P. caucasicus whose sequence was not present in the GenBank. Based on the results of our study, the RFLP-PCR method with nucleotide gene fragment ITS2 was a rapid and reliable method for differentiating these sand fly species.

Genetic variability of populations of Nyssomyia neivai in the Northern State of Paraná, Brazil

The genetic study of sandfly populations needs to be further explored given the importance of these insects for public health. Were sequenced the NDH4 mitochondrial gene from populations of Nyssomyia neivai from Doutor Camargo, Lobato, Japira, and Porto Rico, municipalities in the State ofParaná, Brazil, to understand the genetic structure and gene flow. Eighty specimens of Ny. Neivai were sequenced, 20 from each municipality, and 269 base pairs were obtained. A total of 27 haplotypes and 28 polymorphic sites were found, along with a haplotypic diversity of 0.80696 and a nucleotide diversity of 0.00567. Haplotype H5, with 33 specimens, was the most common among the four populations. Only haplotypes H5 and H7 were present in all four populations. The population from Doutor Camargo showed the highest genetic diversity, and only this population shared haplotypes with those from the other municipalities. The highest number of haplotypes was sheared with Lobato which also had the highest number of unique haplotypes. This probably occurred because of constant anthropic changes that happened in the environment during the first half of the twentieth century, mainly after 1998. There was no significant correlation between genetic and geographical distances regarding these populations. However, the highest genetic and geographical distances, and the lowest gene flow were observed between Japira and Porto Rico. Geographical distance is a possible barrier between these municipalities through the blocking of haplotype sharing.

Identification of Algerian Field-Caught Phlebotomine Sand Fly Vectors by MALDI-TOF MS

BACKGROUND

Phlebotomine sand flies are known to transmit Leishmania parasites, bacteria and viruses that affect humans and animals in many countries worldwide. Precise sand fly identification is essential to prevent phlebotomine-borne diseases. Over the past two decades, progress in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has emerged as an accurate tool for arthropod identification. The objective of the present study was to investigate the usefulness of MALDI-TOF MS as a tool for identifying field-caught phlebotomine.

METHODOLOGY/PRINCIPAL FINDINGS

Sand flies were captured in four sites in north Algeria. A subset was morphologically and genetically identified. Six species were found in these areas and a total of 28 stored frozen specimens were used for the creation of the reference spectrum database. The relevance of this original method for sand fly identification was validated by two successive blind tests including the morphological identification of 80 new specimens which were stored at -80°C, and 292 unknown specimens, including engorged specimens, which were preserved under different conditions. Intra-species reproducibility and inter-species specificity of the protein profiles were obtained, allowing us to distinguish specimens at the gender level. Querying of the sand fly database using the MS spectra from the blind test groups revealed concordant results between morphological and MALDI-TOF MS identification. However, MS identification results were less efficient for specimens which were engorged or stored in alcohol. Identification of 362 phlebotomine sand flies, captured at four Algerian sites, by MALDI-TOF MS, revealed that the subgenus Larroussius was predominant at all the study sites, except for in M'sila where P. (Phlebotomus) papatasi was the only sand fly species detected.

CONCLUSION

The present study highlights the application of MALDI-TOF MS for monitoring sand fly fauna captured in the field. The low cost, reliability and rapidity of MALDI-TOF MS analyses opens up new ways in the management of phlebotomine sand fly-borne diseases.

Mitochondrial genomes of two phlebotomine sand flies, Phlebotomus chinensis and Phlebotomus papatasi (Diptera: Nematocera), the first representatives from the family Psychodidae

BACKGROUND

Leishmaniasis is a worldwide but neglected disease of humans and animal transmitted by sand flies, vectors that also transmit other important diseases. Mitochondrial genomes contain abundant information for population genetic and phylogenetic studies, important in disease management. However, the available mitochondrial sequences of these crucial vectors are limited, emphasizing the need for developing more mitochondrial genetic markers.

METHODS

The complete mitochondrial genome of Phlebotomus chinensis was amplified in eight fragments and sequenced using primer walking. The mitochondrial genome of Phlebotomus papatasi was reconstructed from whole-genome sequencing data available on Genbank. The phylogenetic relationship of 24 selected representatives of Diptera was deduced from codon positions 1 and 2 for 13 protein coding genes, using Bayesian inference (BI) and maximum likelihood (ML) methods.

RESULTS

We provide the first Phlebotomus (P. chinensis and P. papatasi) mitochondrial genomes. Both genomes contain 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and an A + T-rich region. The gene order of Phlebotomus mitochondrial genomes is identical with the ancestral gene order of insect. Phylogenetic analyses demonstrated that Psychodidae and Tanyderidae are sister taxa. Potential markers for population genetic study of Phlebotomus species were also revealed.

CONCLUSION

The generated mitochondrial genomes of P. chinensis and P. papatasi represent a useful resource for comparative genomic studies and provide valuable future markers for the population genetic study of these important Leishmania vectors. Our results also preliminary demonstrate the phylogenetic placement of Psychodidae based on their mitochondrial genomes.

Mitochondrial DNA Intraspecific Variability in Sergentomyia minuta (Diptera: Psychodidae)

Recently, there has been growing interest in analysis of the geographical variation between populations of different Phlebotomus spp. and American sand flies by comparing the sequences of various genes. However, little is known about the genetic structure of the genus Sergentomyia França & Parrot. No study has been carried out on Sergentomyia minuta Rondani. Most authors recognize this as a species with a high degree of morphological polymorphism, and some suspect that there are two subspecies: Se. minuta minuta Rondani in Europe, having about 40 horizontal cibarial teeth (sticks aligned along a straight line in the cibarial cavity), and Se. minuta parroti Adler & Theodor in North Africa, having about 70 cibarial teeth. Here we analyzed phylogeographic patterns using cytochrome b (Cytb) and cytochrome C oxidase I mtDNA for 29 populations from 10 countries: Algeria, Cyprus, France (continental and Corsica), Greece (continental and Crete), Malta, Montenegro, Morocco, Portugal (continental and Atlantic Savage Islands), Spain, and Tunisia. We analyzed intra- and interpopulation patterns of genetic diversity. Our results from Bayesian inference showed a complex genetic structure of Se. minuta with four haplogroups including many different haplotypes. One haplogroup includes all the specimens from North Africa. A second haplogroup includes a few specimens from the south of France, Spain, and one from Portugal. The third includes many specimens from southern France, all the specimens from Corsica, one from Spain, and all specimen from Portugal except one. A fourth branch includes specimens from the Balkans, Malta, Crete, Cyprus, and curiously some from the Atlantic Savage Islands; settlement of the latter population remains unexplained. However, our results suggest that the settlement of the Mediterranean basin could have occurred at the same time for Se. minuta and both Phlebotomus perniciosus Newstead and Phlebotomus ariasi Tonnoir. The spatial distribution of haplotypes was congruent with phylogenetic findings.

Paraphyly of the subgenus Anaphlebotomus and creation of Madaphlebotomus subg. nov. (Phlebotominae: Phlebotomus)

The systematic position of the Malagasy Phlebotomus (Diptera: Psychodidae) species was assessed in molecular phylogenetic studies. Three molecular markers were sequenced: cytochrome b of the mitochondrial DNA; ITS2, and the D8 domain of the ribosomal DNA. The following species were studied: Phlebotomus (Anaphlebotomus) berentiensis, Phlebotomus (Anaphlebotomus) fertei, Phlebotomus (Anaphlebotomus) fontenillei, Phlebotomus (Anaphlebotomus) vaomalalae and Phlebotomus (Anaphlebotomus) vincenti from Madagascar; Phlebotomus (Anaphlebotomus) stantoni from Asia, and Phlebotomus (Anaphlebotomus) rodhaini from Africa. The following outgroups were selected: Phlebotomus (Euphlebotomus) argentipes, Phlebotomus (Euphlebotomus) barguesae, Phlebotomus (Larroussius) perfiliewi s.l. and Phlebotomus (Adlerius) simici. Each marker analysed by maximum parsimony and maximum likelihood supports the monophyly of the Malagasy Phlebotomus spp. Consequently, we create a new subgenus for these species: Madaphlebotomus subg. nov. This molecular individualization is reinforced by the originality of their spermathecae and by the fact that their geographical distribution is limited to Madagascar, and considers the high level of endemism on this island.

Phlebotomus papatasi SP15: mRNA expression variability and amino acid sequence polymorphisms of field populations

Background

The Phlebotomus papatasi salivary protein PpSP15 was shown to protect mice against Leishmania major, suggesting that incorporation of salivary molecules in multi-component vaccines may be a viable strategy for anti-Leishmania vaccines.

Methods

Here, we investigated PpSP15 predicted amino acid sequence variability and mRNA profile of P. papatasi field populations from the Middle East. In addition, predicted MHC class II T-cell epitopes were obtained and compared to areas of amino acid sequence variability within the secreted protein.

Results

The analysis of PpSP15 expression from field populations revealed significant intra- and interpopulation variation.. In spite of the variability detected for P. papatasi populations, common epitopes for MHC class II binding are still present and may potentially be used to boost the response against Le. major infections.

Conclusions

Conserved epitopes of PpSP15 could potentially be used in the development of a salivary gland antigen-based vaccine.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-0914-2) contains supplementary material, which is available to authorized users.

Phylogeography of the Lutzomyia gomezi (Diptera: Phlebotominae) on the Panama Isthmus

BACKGROUND

Lutzomyia gomezi (Nitzulescu, 1931) is one of the main Leishmania (Vianna) panamensis vectors in Panama, and despite its medical significance, there are no population genetic studies regarding this species. In this study, we used the sequences of the mitochondrial gene cytochrome b/start of NADH1 and the nuclear elongation gene α-1 in order to analyze genetic variation and phylogeographic structure of the Lu. gomezi populations.

METHODS

A total of 86 Lu. gomezi individuals were captured in 38 locations where cutaneous leishmaniasis occurred. DNA was extracted with phenol/chloroform methods and amplification of genes was performed using PCR primers for mitochondrial and nuclear markers.

RESULTS

We found a total of 37 and 26 haplotypes of mitochondrial and nuclear genes, high haplotype diversity (h) for all three populations were detected with both molecular markers. Nucleotide diversity (π) was estimated to be high for all three populations with the mitochondrial marker, which was opposite to the estimate with the nuclear marker. In the AMOVA Φst recorded moderate (mitochondrial) and small (nuclear) population structure with statistical significance among populations. The analysis of the fixation index (Fst) used to measure the differentiation of populations showed that with the exception of the population located in the region of Bocas del Toro, the other populations presented with minor genetic differentiation. The median-Joining network of the mitochondrial marker reveled three clusters and recorded four haplotypes exclusively of localities sampled from Western Panama, demonstrating strong divergence. We found demographic population expansion with Fu´s Fs neutrality test. In the analysis mismatch distribution was observed as a bimodal curve.

CONCLUSION

Lu. gomezi is a species with higher genetic pool or variability and mild population structure, due to possible capacity migration and local adaptation to environmental changes or colonization potential. Thus, knowledge of the genetic population and evolutionary history is useful to understand the implications of different population genetic structures for cutaneous leishmaniasis epidemiology.

Molecular and morphological systematics of the sandfly Sergentomyia (Sintonius) clydei Sinton, 1928 and questions about its record in the Seychelles

In the Phlebotomine sandflies, a few molecular studies related on the genus Sergentomyia have been published. The present study explored the genetic variability within Sergentomyia (Sintonius) clydei (Diptera, Psychodidae). The sampling included 15 populations originating from 12 countries. A morphological approach was coupled to the sequencing of two molecular markers (cytochrome b mtDNA and cacophony nuclear DNA). The most variable morphological characters resided in the cibarium of the females, especially (i) the pigment patch pattern and (ii) the number of cibarial teeth and denticles in the armature. However this morphological approach was unable to individualize any population within S. clydei. The NJ trees based on both molecular markers individualized the specimens from the Aldabra group of islands in the Seychelles. Surprisingly, cyt b variability was not compatible with the known data about the complete submersion of Aldabra occurring relatively recently some 125,000 years ago. The settlement of these islands by S. clydei from continental Africa, the Middle East or Asia, and the value of mtDNA markers are discussed.

Molecular identification of potential leishmaniasis vector species within the Phlebotomus (Euphlebotomus) argentipes species complex in Sri Lanka

Background

Leishmaniasis is an emerging vector-borne disease in Sri Lanka. Phlebotomus (Euphlebotomus) argentipes sensu lato Annandale and Brunette 1908 is suspected to be a potential vector. Three sibling species have been reported in the species complex based on analysis of morphological data. A study was carried out in different parts of Sri Lanka including cutaneous leishmaniasis prevailing localities to characterise the sibling species of Phlebotomus (Euphlebotomus) argentipes sensu lato and to establish their possible role in Leishmania transmission.

Methods

Sandflies were collected using cattle baited trap nets and mouth aspirator. They were identified based on existing taxonomic keys. Sequences of amplified cytochrome oxidase subunit I (CO I), cytochrome oxidase b (cyt b), internal transcribed spacer 2 (ITS2), 18s and 28s rDNA regions were analysed to confirm the number of sibling species. Vectorial capacity of the sibling species was checked by detecting human and Leishmania DNA.

Results

Sandflies collected using different techniques were processed for identification, parasite detection and molecular characterization. The 18s, 28s rDNA and cytochrome oxidase subunit I (CO I), internal transcribed spacer 2 (ITS2) and cytochrome b oxidase (cytb) sequences confirmed that the species belonged to the Argentipes complex. 18s and 28s sequences did not show any variation among the proposed sibling species. The phylogeny created from mitochondrial CO I and cytochrome b data and from the nuclear ITS2 region supports the existence of only two groups of flies (termed A and B) from Phlebotomus (Euphlebotomus) argentipes complex instead of the previously proposed three. The Leishmania mini-circle kinetoplastid, heat shock protein 70 (hsp70) and internal transcribed spacer I DNA along with human blood were detected from sibling species A only, which has not previously been considered to be a vector.

Conclusions

The taxonomy of the Sri Lankan Argentipes species complex is reassessed based on the molecular data. The existence of two sibling species is proposed; sibling species A has a long sensilla chaetica (> 50% length of the second antennal flagellomere) and sibling species B has a short sensilla cheatica (< 50%). Sibling species A is incriminated as a vector for leishmaniasis in Sri Lanka.

The distribution of the Phlebotomus major complex (Diptera: Psychodidae) in Turkey

The taxonomic status and distribution of the morphologically similar members of the Phlebotomus major complex in Turkey are unclear. To examine the utility of traditional morphological characters and molecular markers, sand flies were sampled from 90 localities in eleven different provinces covering a wide geographical range throughout Turkey. The morphometric variability was analysed using multivariate analyses of twelve characters, while mitochondrial cytochrome b (Cyt b) and nuclear elongation factor 1α (EF 1-α) genes were used for molecular discrimination. Three distinct monophyletic lineages were identified based on the phylogenetic analysis of the combined data set of mitochondrial and nuclear gene regions, which were also supported by parsimony haplotype network analysis and AMOVA of Cyt b. The first lineage is restricted to south eastern Turkey and represents the species Phlebotomus syriacus, the second is present mostly in the westernmost and the easternmost localities and represents P. neglectus, and the third member of this complex is distributed across the mid-northern and mid-southern regions. None of the studied morphological characters were found to be sufficient to discriminate between these three members of the P. major s.l. complex; however their presence sympatrically in several localities supports their status as species rather than inter-population variability.

WITHDRAWN: Epidemiological role of Phlebotomus papatasi and P. sergenti populations in Morocco: What we know and what can we learn from the field?

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Genetic differentiation between sandfly populations of Phlebotomus chinensis and Phlebotomus sichuanensis (Diptera: Psychodidae) in China inferred by microsatellites

Background

Phlebotomus chinensis is a primary vector of visceral leishmaniasis; it occurs in various biotopes with a large geographical distribution, ranging from Yangtze River to northeast China. Phlebotomus sichuanensis, a species closely related to P. chinensis in high altitude regions, has a long term disputation on its taxonomic status. Both species occur in the current epidemic regions and are responsible for the transmission of leishmaniasis. Population genetic analysis will help to understand the population structure and infer the relationship for morphologically indistinguishable cryptic species. In this study, microsatellite markers were used for studying the genetic differentiation between P. chinensis and P. sichuanensis.

Methods

Sandflies were collected in 6 representative localities in China in 2005-2009. Ten microsatellite loci were used to estimate population genetic diversity. The intra-population genetic diversity, genetic differentiation and effective population size were estimated.

Results

All 10 microsatellite loci were highly polymorphic across populations, with high allelic richness and heterozygosity. Hardy-Weinberg disequilibrium was found in 23 out of 60 (38.33%) comparisons associated with heterozygote deficits, which was likely caused by the presence of null allele and the Wahlund effect. Bayesian clustering analysis revealed three clusters. The cluster I included almost all specimens in the sample SCD collected at high altitude habitats in Sichuan. The other two clusters were shared by the remaining 5 populations, SCJ in Sichuan, GSZ in Gansu, SXL and SXX in Shaanxi and HNS in Henan. The diversity among these 5 populations was low (F_ST = -0.003-0.090) and no isolation by distance was detected. AMOVA analysis suggested that the variations were largely derived from individuals within populations and among individuals. Consistently, the analysis of ribosomal DNA second internal transcribed spacer (ITS2) sequence uncovered three types of variants, which corresponded with the three gene pools revealed by microsatellites.

Conclusions

The data suggested that the SCD population carried a distinct gene pool, which was differentiated from the other populations. The high altitude ecological habitats, distinctive ITS2 and herein divergence inferred by microsatellite loci support the species status of P. sichuanensis. The P. chinensis populations did not have a significant divergence from each another.

Leishmania development in sand flies: parasite-vector interactions overview

Leishmaniases are vector-borne parasitic diseases with 0.9 - 1.4 million new human cases each year worldwide. In the vectorial part of the life-cycle, Leishmania development is confined to the digestive tract. During the first few days after blood feeding, natural barriers to Leishmania development include secreted proteolytic enzymes, the peritrophic matrix surrounding the ingested blood meal and sand fly immune reactions. As the blood digestion proceeds, parasites need to bind to the midgut epithelium to avoid being excreted with the blood remnant. This binding is strictly stage-dependent as it is a property of nectomonad and leptomonad forms only. While the attachment in specific vectors (P. papatasi, P. duboscqi and P. sergenti) involves lipophosphoglycan (LPG), this Leishmania molecule is not required for parasite attachment in other sand fly species experimentally permissive for various Leishmania. During late-stage infections, large numbers of parasites accumulate in the anterior midgut and produce filamentous proteophosphoglycan creating a gel-like plug physically obstructing the gut. The parasites attached to the stomodeal valve cause damage to the chitin lining and epithelial cells of the valve, interfering with its function and facilitating reflux of parasites from the midgut. Transformation to metacyclic stages highly infective for the vertebrate host is the other prerequisite for effective transmission. Here, we review the current state of knowledge of molecular interactions occurring in all these distinct phases of parasite colonization of the sand fly gut, highlighting recent discoveries in the field.

Evidence for genetic differentiation at the microgeographic scale in Phlebotomus papatasi populations from Sudan

Background

Cutaneous Leishmaniasis (CL) is endemic in Sudan. It is caused by Leishmania major parasites and transmitted by Phlebotomus papatasi sandflies. Recently, uncommon clinical manifestations of CL have been reported. Moreover, L. donovani parasites that cause Visceral Leishmaniasis (VL) have been isolated from CL lesions of some patients who contracted the disease in Khartoum State, Central Sudan with no history of travelling to VL endemic sites on south-eastern Sudan. Because different clinical manifestations and the parasite behaviour could be related to genetic differentiation, or even sub-structuring within sandfly vector populations, a population genetic study was conducted on P. papatasi populations collected from different localities in Khartoum State known for their uncommon CL cases and characterized by contrasting environmental conditions.

Methods

A set of seven microsatellite loci was used to investigate the population structure of P. papatasi samples collected from different localities in Khartoum State, Central Sudan. Populations from Kassala State, Eastern Sudan and Egypt were also included in the analyses as outgroups. The level of genetic diversity and genetic differentiation among natural populations of P. papatasi was determined using F_ST statistics and Bayesian assignments.

Results

Genetic analyses revealed significant genetic differentiation (F_ST) between the Sudanese and the Egyptian populations. Within the Sudanese P. papatasi populations, one population from Gerif West, Khartoum State, exhibited significant genetic differentiation from all other populations including those collected as near as 22 km.

Conclusion

The significant genetic differentiation of Gerif West P. papatasi population from other Sudanese populations may have important implication for the epidemiology of leishmaniasis in Khartoum State and needs to be further investigated. Primarily, it could be linked to the unique location of Gerif West which is confined by the River Nile and its tributaries that may act as a natural barrier for gene flow between this site and the other rural sites. The observed high migration rates and lack of genetic differentiation among the other P. papatasi populations could be attributed to the continuous human and cattle movement between these localities.

Courtship behaviour of Phlebotomus papatasi the sand fly vector of cutaneous leishmaniasis

Background

The sand fly Phlebotomus papatasi is an Old World vector of Leishmania major, the etiologic agent of zoonotic cutaneous leishmaniasis. This study describes the courtship behaviour of P. papatasi and compares it with that of Lutzomyia longipalpis, the New World vector of visceral leishmaniasis. Understanding the details of courtship behaviour in P. papatasi may help us to understand the role of sex pheromones in this important vector.

Results

P. papatasi courtship was found to start with the female touching the male, leading him to begin abdomen bending and wing flapping. Following a period of leg rubbing and facing, the male flaps his wings while approaching the female. The female then briefly flaps her wings in response, to indicate that she is willing to mate, thereby signaling the male to begin copulation. Male P. papatasi did not engage in parading behaviour, which is performed by male L. longipalpis to mark out individual territories during lekking (the establishment and maintenance of mating aggregations), or wing-flap during copulation, believed to function in the production of audio signals important to mate recognition. In P. papatasi the only predictor of mating success for males was previous copulation attempts and for females stationary wing-flapping. By contrast, male L. longipalpis mating success is predicted by male approach-flapping and semi-circling behaviour and for females stationary wing-flapping.

Conclusions

The results show that there are important differences between the mating behaviours of P. papatasi and L. longipalpis. Abdomen bending, which does not occur in L. longipalpis, may act in the release of sex pheromone from an as yet unidentified site in the male abdomen. In male L. longipalpis wing-flapping is believed to be associated with distribution of male pheromone. These different behaviours are likely to signify significant differences in how pheromone is used, an observation that is consistent with field and laboratory observations.

A study of a population of Nyssomyia trapidoi (Diptera: Psychodidae) caught on the Pacific coast of Ecuador

Background

Cutaneous leishmaniasis is endemic to the Pacific coast of Ecuador, and Nyssomyia trapidoi is considered to be its main vector. Dujardin et al. [1] recorded some differences in body pigmentation and isoenzymatic profiles in sympatric populations of Ny. trapidoi from the Pacific coast of Ecuador and suggested the existence of two cryptic species.

Methods

Entomological collections were performed in November 2008 and March 2011 in the locality of Paraíso Escondido using CDC miniature light traps and human bait. Morphological, isoenzymatical and molecular (sequencing of cytochome b and cytochrome c oxidase 1 of the mitochondrial DNA) analyses, such as detection of Leishmania DNA and phlebovirus RNA in some females, were performed.

Results

Neighbor-joining trees from mitochondrial sequences grouped all of Ecuadorian Ny. trapidoi (including the two color variants) in one cluster, except for two specimens which clustered separately in both genes. Isoenzymatic characterization confirmed that the color variants belong to the same population. Additionally, 11.5% of females were found by PCR to contain Endotrypanum monterogeii kinetoplastid DNA. All pools of Ny. trapidoi were negative for phlebovirus RNA.

Conclusion

Analysis of mitochondrial gene sequences and isoenzymes was unable to support the existence of two sibling species within Ny. trapidoi, which is a probable vector of Endotrypanum monterogeii.

Wing size and shape variation of Phlebotomus papatasi (Diptera: Psychodidae) populations from the south and north slopes of the Atlas Mountains in Morocco

The wing shape and size morphology of populations of the medically important phlebotomine sand fly, Phlebotomus papatasi, were examined in two endemic (south of the Atlas Mountains) and nonendemic (north of the Atlas Mountains) foci of cutaneous leishmaniasis by using geometric morphometrics in Morocco. Although it is present in all of Morocco, P. papatasi is the main vector of Leishmania major in only southern part of the Atlas Mountains. There are four major mountain ranges that serve as geographical barriers for species distribution in the study area and at least four gaps were recognized among these barriers. We found statistically significant differences in wing shape morphology between southern and northern populations. Analysis clearly recognized two main groups of populations on both sides of the mountains. The graphical depiction of Principal Component Analysis (PCA) and Canonical Variates Analysis (CVA) confirmed our morphometric study suggesting that the difference in wing morphology between the populations indicates that the population of P. papatasi shows phenotypic plasticity in the study area. According to centroid size analyses, which were used as measures of wing size differences among different sites, the north population of P. papatasi had relatively larger wings than the south population.

Morphological and anatomical variations among Phlebotomus (Phlebotomus) papatasi sensu lato (Diptera: Psychodidae)

Phlebotomus (Phlebotomus) papatasi (Scopoli) collected in human dwellings from an agricultural villages Chaura, located in Gaya district, Bihar, India, showed morphological and anatomical variations. Male sand flies of this species exhibited variations in the genital structures, while females showed differences in the spermathecae and antenna segment three (A3). When the mitochondrial DNA of both male and female P. (P.) papatasi sensu lato population subjected to DNA barcoding, both the sexes of P. (P.) papatasi variants were found to be associated. The differences in the morphometric characteristics clearly constitutes preliminary evidence for infraspecific variation in P. (P.) papatasi s.1. population in India.

Individual variability of salivary gland proteins in three Phlebotomus species

Pooled salivary gland samples are frequently used to ensure the sufficient amount of material for the experiments; however, this could mask an individual variability. Thus, we compared salivary protein profiles in seven colonies of three Phlebotomus species: Phlebotomus sergenti, Phlebotomus perniciosus, and Phlebotomus papatasi. Surprisingly, the individual profiles differed significantly between the colonies as well as between individuals. The highest variability was observed in proteins with molecular masses of 42-46 kDa corresponding to the yellow-related proteins. The phenogram constructed from salivary gland profiles revealed the existence of two main groups in P. sergenti, corresponding well with the geographical origin. The F1 progeny obtained from cross-mating studies between P. sergenti colonies of different geographical origin formed a distinct subgroup within the parental groups. In P. papatasi, several groups of protein profiles were observed with no relationship to the geographical origin. The biological role of salivary proteins variability is discussed.

DNA sequence variation of the tobacco cutworm, Spodoptera litura (Lepidoptera: Noctuidae), determined by mitochondrial A+T-rich region and nuclear ITS2 sequences

In an effort to gain greater insight into the nature of the population genetic structure of the pest insect Spodoptera litura (Lepidoptera: Noctuidae), tobacco cutworms were collected from six Korean and five Chinese localities, and their mitochondrial A+T-rich region and nuclear internal transcribed spacer 2 (ITS2) were cloned and sequenced. The A+T-rich region and nuclear ITS2 provided a maximum sequence divergence of 2.88 and 1.82%, respectively. Overall, a low level of genetic fixation (F(ST) = 0-0.02965 in the A+T-rich region and 0-0.34491 in ITS2) and no discernible isolated population were noted among most S. litura populations. Along with these results, the absence of genetic variance between Korea and China indicates a profound interrelation of the S. litura populations in the two countries, consistent with the current notion that S. litura has sufficient flight capacity for dispersal.

Expression plasticity of Phlebotomus papatasi salivary gland genes in distinct ecotopes through the sand fly season

BACKGROUND

Sand fly saliva can drive the outcome of Leishmania infection in animal models, and salivary components have been postulated as vaccine candidates against leishmaniasis. In the sand fly Phlebotomus papatasi, natural sugar-sources modulate the activity of proteins involved in meal digestion, and possibly influence vectorial capacity. However, only a handful of studies have assessed the variability of salivary components in sand flies, focusing on the effects of environmental factors in natural habitats. In order to better understand such interactions, we compared the expression profiles of nine P. papatasi salivary gland genes of specimens inhabiting different ecological habitats in Egypt and Jordan and throughout the sand fly season in each habitat.

RESULTS

The majority of investigated genes were up-regulated in specimens from Swaymeh late in the season, when the availability of sugar sources is reduced due to water deprivation. On the other hand, these genes were not up-regulated in specimens collected from Aswan, an irrigated area less susceptible to drought effects.

CONCLUSION

Expression plasticity of genes involved with vectorial capacity in disease vectors may play an important epidemiological role in the establishment of diseases in natural habitats.